[Proc. Roy. Soc. Victoria, 21 (N.S.), Pt. I., 190SS.] 



Art. III. — Tlie Body Spaces and so-called Excretory 

 Organs of Ihla quadrlvalvis. 



By FREDA BAGE, M..Sc. 



(Bioloi^ical Laboratory, Melbourne University). 



(With Plate VI.)- 



[Eead 12th March, 1908.] 



Since the publication of Darwin's Monofrraph of the Cirri- 

 pedia [2] a gi*eat deal of work has been done on these forms, 

 "which have a number of organs whose function is either unknown 

 or disputed. The following work on the body spaces and so- 

 called excretory organs of Ibla, quadriralvis has been done in the 

 Biology School, University of Melbiiurne,. at the instigation and 

 under the supervision of Professor Baldwin Spencer, in order to 

 try and clear up, for this form at least, some of these uncertain 

 points. So far as I am aware, this species has not been worked 

 before, and I have been fortunate in having a practically un- 

 limited number of specimens at my disposal, as it is common 

 near Melbourne. Tlio investigation has been carried on by 

 means of a sei'ies of serial sections cut transversely and longi- 

 tudinally, but the toughness of the tissues renders it exceedingly 

 difficult to secure good serial sections. 



Ibla quadrivalvis grows attached to rocks in smaller or larger 

 clusters below high-water mark. It is a pedunculated Cirripede, 

 the peduncle being surmounted by two paii's of valves, and con- 

 taining in its upper part the body of the animal. 



The general body cavity is, as in all Arthropoda, a hieinnc<ole 

 forming more or less irregular spaces in the loose tissue which 

 connects the various organs of the body. In all the series, how- 

 eiver, in addition to the lijemocoele, two definitely walled spaces 

 attract attention at once, and it is these and their relations to 

 other structures which are the subject of the present work. 



Attached to the base of the second maxilla, and between it 

 and the inner maxilla, on each side of the mouth, is a tubular 



